Hi Vijay,
On 22/09/2015 10:55, Vijay Kilari wrote:
On Mon, Sep 21, 2015 at 4:53 PM, Julien Grall <[email protected]> wrote:
Hi Vijay,
The only things I haven't check on this patch was the ITS command structure.
[...]
Why a padding of only 56 bits? Shouldn't it be 248 bits (i.e 31 * 8
bits) to fit all the command?
+ } hdr;
+ struct __packed {
+ u8 cmd;
+ u8 res1[3];
+ u32 devid;
+ u64 size:5;
+ u64 res2:59;
+ /* XXX: Though itt is 40 bit. Keep it 48 to avoid shift */
+ u64 res3:8;
It's very confusing for the reviewer to see a mix of usage (u8 res1[n],
u64 res3:8) within the same structure.
The later (i.e u64 field:n) is the best to use because we can match
quickly the size with the spec.
Do you mean to convert all field type as 64 as below?
Yes.
struct __packed {
u64 cmd:8;
u64 res:24;
u64 devid:32;
u64 size:5;
u64 res2:59;
/* XXX: Though itt is 40 bit. Keep it 48 to avoid shift */
BTW, this comment is not clear. Please explain in the comment why you
want to use 48 bit. I.e
"XXX: The ITT holds the upper bits of the address [47-8]. Include res3
to avoid shifting?"
u64 res3:8;
u64 itt:40;
u64 res4:15;
u64 valid:1;
u64 res5;
} mapd_cmd;
Regards,
--
Julien Grall
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